LTC1069-6
7
10696fa
APPLICATIONS INFORMATION
Temperature Behavior
The power supply current of the LTC1069-6 has a positive
temperature coeffi cient. The GBW product of its internal
op amps is nearly constant and the speed of the device
does not degrade at high temperatures. Figures 4a, 4b
and 4c show the behavior of the passband of the device
for various supplies and temperatures. The fi lter has a
passband behavior which is temperature independent.
Clock Feedthrough
The clock feedthrough is defi ned as the RMS value of the
clock frequency and its harmonics that are present at the
fi lter’s Output (Pin 8). The clock feedthrough is tested with
the Input (Pin 4) shorted to AGND (Pin 1) and depends on
PC board layout and on the value of the power supplies.
With proper layout techniques the values of the clock
feedthrough are shown in Table 2.
Table 2. Clock Feedthrough
V
S
CLOCK FEEDTHROUGH
3.3V 100μV
RMS
5V 170μV
RMS
10V 350μV
RMS
Any parasitic switching transients during the rising and
falling edges of the incoming clock are not part of the
clock feedthrough specifi cations. Switching transients
have frequency contents much higher than the applied
clock; their amplitude strongly depends on scope probing
techniques as well as grounding and power supply
bypassing. The clock feedthrough can be reduced by adding
a single RC lowpass fi lter at the Output (Pin 8).
FREQUENCY (kHz)
1
GAIN (dB)
1
2
17
1069-6 F04a
0
–1
–2
5
9
13
319
7
11
15
21
V
S
= SINGLE 3V
V
IN
= 0.5V
RMS
f
CLK
= 500kHz
f
CUTOFF
= 10kHz
85°C
–40°C
Figure 4a
FREQUENCY (kHz)
1
GAIN (dB)
1
2
17
1069-6 F04a
0
–1
–2
5
9
13
319
7
11
15
21
V
S
= SINGLE 5V
V
IN
= 1V
RMS
f
CLK
= 750kHz
f
CUTOFF
= 15kHz
85°C
–40°C
FREQUENCY (kHz)
1
GAIN (dB)
1
2
25
1069-6 F04c
0
–1
–2
7
13
19
428
10
16
22
31
V
S
= ±5V
V
IN
= 1.5V
RMS
f
CLK
= 1MHz
f
CUTOFF
= 20kHz
85°C
–40°C
Figure 4b
Figure 4c
